As a countermeasure against power failure in a magneto-optical disk drive apparatus, there has been known firstly a method of writing data before occurrence of power failure in a non-volatile memory during magnetic recording and writing data from this non-volatile memory into a specified memory when power supply is restored (Refer to, for instance, Japanese Patent Publication No. 2202/1990).
However, in this first method, a non-volatile memory is required, and when a capacity of a buffer memory is large, it is required to use a non-volatile memory having the same capacity, the cost becomes expensive, and in addition it is necessary to provide a non-volatile memory in the data recording device, so that the method can not always be applied to all types of data recording devices based on the conventional technology.
Secondly, there has been known a method of executing carriage unload from a home position to a lock position at a specified reference speed when power is turned OFF (Refer to, for instance, Japanese Patent Laid Open Publication No. 311677/1988).
This second method is for unloading a carriage upon power turn OFF, so that protection of write data during power failure is impossible.
Thirdly, a method of tracking in a sector which recording was made finally during recording operation down has been known (Refer to, for instance, Japanese Patent Publication No. 48576/1991).
In this third method, only a beam position is returned to a relative position of a beam to a disk, so that protection of write data during power failure is also impossible like in the second method.
Fourthly, there is a method of automatically locking an optical head to a given position when power supply is turned OFF (Refer to, for instance, Japanese Patent Laid Open Publication No. 201579/1985).
Also in this fourth method, only a beam position is fixed at a relative position of a beam to a disk when power failure occurs, so that protection of write data during power failure is impossible like in the second method.
As described above, in the conventional types of magneto-optical disk drive apparatus as described above, various types of countermeasure have been proposed against power failure, but any countermeasure is not effective for write data protection.
For this reason, disadvantageously there has been no magneto-optical disk drive apparatus which makes it possible to write write data safely and accurately in a storage medium during power failure.